Conventional displays are flat panel displays, and cannot be bent arbitrarily. A development trend of displays is to display lots of information on a flexible body, i.e. a flexible display. The flexible display and flexible display module can be mechanically bent in any of the steps such as substrate packaging, production, storage, use, operation, process connection, handling, and transportation. The key technologies for achieving the flexible display include: display technology, substrate technology, array technology and encapsulation technology. At present, the substrate that can be used in the flexible display mainly includes: ultrathin glass substrate, metal foil substrate and plastic substrate. Plastic substrates (generally, PEN, PET, PI, PC and the like are used) have better flexibility, lighter weight, higher impact resistance, and are suitable for manufacturing thinner devices, thus becoming the development trend of flexible display technology.
However, plastic is an organic material, and water vapor and oxygen may easily penetrate the plastic and thus affect the quality of flexible display panels, especially the performances of OLEDs, TFTs. Even if a barrier layer is attached on a back side, water vapor/oxygen will also enter from an edge side to affect the quality of the product.